Multilateral Agreement M-291 in accordance with section 1.5.1 of Annex A of the European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR), regarding packaging instruction P502 for UN 1873, made in Madrid on April 13, 2016.
Link: https://www.boe.es/boe/dias/2016/06/15/pdfs/BOE-A-2016-5800.pdf